The present invention relates to a backlash-free reducing mechanism, particularly usable for setting various parts of a seat of an automobile vehicle.
Most continuous setting mechanisms for automobile vehicle seats use reducing devices with gear trains including generally a single planet wheel. Unfortunately, the disadvantage of this is to create radial forces in the control system, which radial forces are not balanced and are both detrimental to an operation under loads and responsible for the creation of large backlashes.
The mechanism which the invention is directed to is a reducing mechanism including two imbricated gear trains, the inner efforts of which are balanced due to the action of several planet wheels.
Such a type of reducing mechanism is known, but it is the principle which makes it backlash-free which is the subject matter of this invention.
The leading idea of the invention is to resiliently eliminate the undesirable backlashes of the reducing mechanism while preserving realistic manufacturing tolerances.
The basic reducing mechanism includes two flanges, one called the fixed flange and the other called the mobile flange, and which are both provided with an inner toothing defining two rings. These two rings can possibly have a different number of teeth, or the same number of teeth, and inside these two flanges are mounted at least four planet wheels.
Each planet wheel has two toothings having generally a different number of teeth and placed on either side of a cylindrical support element: they are therefore called double planet wheels.
These planet wheels first mesh with the two rings and, also on either side of the cylindrical support elements, with a central pinion. One of these two pinions is intended for being a control member for the receiving mechanism, the other pinion being maintained free in rotation.
Finally, a planet wheel holding piece is intended for receiving the planet wheel cylindrical support elements.
Due to the manufacturing and assembly tolerances, such a reducing mechanism presents of course a beating backlash between the two flanges.